QSB QSL CM2250 - Fuel Systems [PDF]

Zitiervorschau

QSB6.7 & QSL9 CM2250 Fuel Systems

HPCR Fuel System Safety
Wear your safety glasses
Use cardboard or paper for

identifying/troubleshooting high-pressure leaks ... Never use your hands or fingers


1800 bar = 26,106 PSI
2 Bar (30 PSI) is enough to penetrate human skin

and cause a pressure injection.
Always wait at least 10 minutes following engine shut down before opening the high pressure fuel system for QSB6.7. The QSL9 fuel system can be safely vented when the procedure is followed.
If possible, use INSITE to monitor the fuel pressure to ensure it is safe to open the system
Never place your hands near fuel system fittings when loosening them 2

Fuel System Clean Care
Clean all fuel system fittings, lines, and components before disassembly.
Make sure that no dirt or debris enters the fuel system components to prevent the passing of contaminants to the high pressure fuel rail and injectors.
Small amounts of dirt and debris can cause a malfunction of these components.
QSB6.7 & QSL9 CM2250 have clean care kits available

3

Clean Care Review
Questions:
What is a micron?
What are potential sources of fuel



4

system contamination? What can you as the technician do to prevent fuel system contamination? Do you always pre-fill fuel filters?

Fuel Specifications
Engines equipped with exhaust aftertreatment must operate on ultra-low sulfur diesel (ULSD), with a maximum sulfur content of 15 ppm in the US and Canada, and 10 ppm in Europe. Failure to do so will result in damage to the aftertreatment system.
The machine OEM is required to display readily visible labels on the dashboard (or instrument panel), and near all fuel fill inlets that states "Use Ultra Low-sulfur Diesel Fuel Only" or "Ultra Low-Sulfur Diesel Fuel Only".
ULSD / Biodiesel blends up to B20 (20% biodiesel) supplied by a BQ9000 certified supplier are acceptable. 5

Ultra Low Sulfur Diesel Fuel Could today’s fuel be used in Tier 4 Interim engines?
Tier 4 Interim engines must use ULSD. It is not possible to comply with the legally required PM emissions standard with today’s off-highway fuel which has a higher sulfur content. What happens if higher sulfur fuel is inadvertently used?
A one time inadvertent tank of diesel fuel with greater than 15-ppm sulfur content will not damage the engine and aftertreatment system. The system will clean itself out when ULSD is re-introduced.
Continued improper fuel use of sulfur levels greater than 15-ppm with Cummins Tier 4 Interim engines can permanently damage the engine and aftertreatment systems within a short period of time. Is the engine warranty affected if ULSD is not used?
Yes. Improper fuel use of sulfur levels greater than 15-ppm with Cummins Tier 4 Interim engines can result in denial of warranty coverage for any damage caused by using fuel with sulfur content greater than 15 ppm.

6

Pressure Side Fuel Filtration
Provided by Cummins
5 Micron rating QSB
3 Micron rating QSL
Engine or remote mounted options
Must never be prefilled

7

Why is pre-filling pressure-side fuel filters not recommended?
Normal System operation
Fuel from the suction side filter has been filtered, but not at the micron level the fuel system requires Fuel entering filter head and filter Fuel passing through the filter media Fuel cleaned to the final micron level 8

Dirty Side of Filter Clean Side of Filter

Continued …


What really happens during pre-filling?
During pre-filling the “clean side” of the filter is exposed to any contamination in the fuel supply source

Contamination happens that quickly Both sides of the filter media are exposed to unfiltered fuel Critical system parts are now at risk

Fuel from pre-fill source Fuel passing through the filter media

9

QSB6.7 CM2250 Fuel System Specifications







High-pressure common rail (HPCR) system 1800 Bar System Pressure Single-Stage High Pressure Relief Valve Full authority electronic control of injectors Manually primed fuel system Engine mounted and off engine mounted suction side fuel filter options
The suction side fuel filter must include: – Water separator – Water-in-fuel (WIF) sensing features


Optional 12 or 24 VDC fuel heater is available from Cummins 10

Priming Pump – QSB6.7 CM2250 engines do not utilize an electric motor driven lift pump. – The OEM installed hand priming pump is used to prime the fuel system. It can be remote or mounted on the engine. – During normal engine operation, the gear pump mounted on the fuel pump will draw fuel from the OEM fuel tank 11

QSB6.7 CM2250 Fuel System Flows Supply Fuel 25 Micron Filtered Fuel 5 Micron Filtered Fuel High Pressure Fuel Return Fuel

QSB6.7 Fuel Flows


Shop Activity – Review Fuel System Flows on Training Engine • ISB6.7 CM2150 and ISB6.7 CM2250 engines have an identical fuel system

13

QSL9 CM2250 Fuel System Specifications
Cummins Designed and Manufactured System




14

– 2100 Bar Operation Pressure – Dual Stage Fuel Rail Relief Valve (Like QSC/L CM850) – Cummins Injectors – New Block-off tool required 4918563 Fuel Pump has modular repair options – Pump assembly – Cam & Cam housing – Actuator or Actuator and Actuator Housing – Gear Pump – Fuel Pump Head

Fuel Pressure Relief Procedure

Cylinder Head Side of Fuel Rail

As the highFuel pressure supply line is Pressure Relief After pressure has been safely vented loosened from the Fuel Rail any Machining on the cylinder from the fuel rail repair or diagnostic pressure inhead the rail will have a Rail side of the Fuel work can begin controlled leak path

15

Fuel Pressure Relief Procedure – Due to the design of the CM2250 fuel system, residual pressure may remain on the high pressure side of the fuel system after engine shutdown – Before servicing any components on the high pressure side of the fuel system, the system pressure should be vented by loosening the fuel pump to fuel rail fuel line • A machined slot in the fitting will direct the fuel spray towards the engine block

16

QSL CM2250 Fuel Pressure Relief Valve

– Dual Stage • Opens at approximately 2600 bar • Regulates to approximately 850 bar when in open position

– Location at the flywheel end of the fuel rail

17

QSL CM2250 Fuel Pressure Relief Valve

18

QSL CM2250 Fuel Pressure Relief Valve Normal Operation

19

QSL9 Fuel Pressure Relief Valve

20

QSL9 Fuel Pressure Relief Valve

21

Cummins ISC/L CM850, QSC/L CM850/2250, ISL CM850 & ISC/L CM2150

+ -

0.043 Diagnostic Orifice

Diagnostic Drain Flow

High Pressure Pump

OEM Responsibility OEM Inlet

OEM Supply Tank

Suction Side Filter

Pressure Side Filter Fuel Rail Relief Valve Return High Pressure Pump Return Injector Return

OEM Return 22

QSL9 CM2250 Fuel Flows


Shop Activity – Review fuel flows on training engine • ISC8.3CM2150, ISL8.9 CM2150, ISC8.3 CM2250, and ISL9 CM2250 have an identical fuel system

23

QSB/L Fuel System Troubleshooting


Major changes to troubleshooting procedures from QSB/L CM850 to QSB/L CM2250 – Both engines feature higher fuel system pressures – QSL is now an all Cummins fuel system – INSITE Fuel System Leakage Test now commands a higher pressure to find higher performance related leaks – New tools

24

Cummins High Pressure Common Rail Injector Theory of Operation

• Injector Solenoid is not energized. The solenoid spring forces the solenoid in the closed position

+ -

• Equal fuel pressure is exerted on both the plunger (1) and shoulder area (2) of the needle • The greater surface area of the plunger (2) results in more hydraulic advantage keeping the injector in the closed position

1

2

• When the ECM requires fuel for a cylinder a voltage is driven to the injector solenoid

+ -

• This creates an electromagnetic force that is greater than the force of the spring •This forces the solenoids metal core to move upward • As the solenoid lifts a leak path is opened in the fuel injector

Fuel from the leak path drains through a passage in the cylinder head

• The leak results in the shoulder of the injector needle now seeing a greater hydraulic force than the plunger (due to the leak path) • This allows the needle to lift from the closed position • Fuel is then injected into the cylinder through the nozzles

+ -

• When fuel is no longer needed the injector solenoid is de-energized by the ECM • The electromagnetic force is removed allowing the spring to force the solenoid to the closed position • When the solenoid is in the closed position the leak path is removed • With the leak path removed the greater surface area of the plunger causes the plunger/needle to reseat and end fuel injection

+ -

• Equal fuel pressure is again sent to both the plunger (1) and shoulder of the needle (2) • The greater surface area of the plunger (1) results in more hydraulic force keeping the injector in the closed position until the ECM determines fueling is again needed

+ -

1

2

• Fuel System cleanliness is very important for High Pressure Common Rail Systems • Contaminants can lodge in the small passages in the injector preventing critical flows • If the contaminate particle lodges in the passage to the plunger area •The result is the injector will remain in the open position and cause engine damage due to uncontrolled fueling of the cylinder

+ -

Fuel Injector / Connector


The high-pressure connector and injector must be replaced if failure is observed •




The high-pressure connector should be replaced anytime the injector is replaced

Be sure not to over torque the connector retaining nut. Over torquing the retaining nut may cause the connector to rotate out of the connector retaining slot.

High Pressure Connector

Fuel Injector Supply Lines Injector supply lines designed for the 1600 Bar fuel rail pressure



No isolators or external supports Injector supply line torque value is critical

A crow's foot and socket extension may be required to remove and install the fuel line fitting to the fuel connector. Anytime a high pressure injector supply line is removed from the engine, the fuel connector nut at the cylinder head must be retorqued.

Fuel System Diagnostics

Fuel System Service Tools Fuel System Leak Tester Commonly called a “Blockoff tool” Used to isolate individual cylinders to determine the location of any system leakage Should be cleaned with contact cleaner prior to use to prevent high pressure fuel system contamination

Fuel System Service Tools Fuel Return Flow Hose Used to check leakage form the high pressure fuel rail’s high pressure relief valve

Fuel System Service Tools Fuel Return Flow Test Kit Allows isolation of high pressure fuel pump and injector return fuel flows

Fuel System Service Tools Fuel Drain Hoses Male and female drain hoses are available Allows testing from quick disconnect 5/16” fuel fittings

Fuel System Service Tools Fuel Tube Plug Used to plug male 5/16” quick disconnect fuel lines during system testing

Fuel System Service Tools Torque Wrench Special torque wrench used for tightening injector terminal nuts 13 in-lb Specification Over tightening the terminal nuts can result in injector solenoid damage The solenoid is not a serviceable part

Fuel System Service Tools Fuel Connector Remover Used to remove high pressure connectors from the cylinder head Prevents damage to connector bore and connector from improvised tools Should be cleaned with contact cleaner prior to use to prevent high pressure fuel system contamination

High Pressure Common Rail CYL Head Fuel Rail Pressure Relief Valve

QSB CM2250 Engine

High Pressure Fuel Line to Rail

Injectors

High Pressure Connectors

Pressure Filter

Fuel Return

Fuel Return

Fuel Return

Fuel Return

Hand Primer Pump Fuel Out

Suction Filter

H.P. Fuel Pump

Fuel Gear Pump

Fuel Tank

High Pressure Common Rail CYL Head Fuel Rail Pressure Relief Valve

QSB CM2250 Engine

High Pressure Fuel Line to Rail

Injectors

High Pressure Connectors

Pressure Filter

Fuel Return

Hand Primer Pump

H.P. Fuel Pump

Injector Return

HP Relief Return

Fuel Tank

HP Pump Return

Fuel Gear Pump

Suction Filter

Fuel Out

High Pressure Common Rail CYL Head Fuel Rail Pressure Relief Valve

ISB CM2150 Engine

High Pressure Fuel Line to Rail

Block Off Tool

Injectors

High Pressure Connectors

Secondary Filter

Fuel Return

Hand Primer Pump

H.P. Fuel Pump

Fuel Tank

Injector Return

Fuel Gear Pump

Primary Filter

Fuel Out

HPCR Theory of Operation

OUT

IN

Pressure-Side Filter

Return Supply

Shop Activity


Perform Procedure 005-236 Fuel System Diagnostics
Discuss differences between QSB and QSL systems

47

Return to Supply

QSL9 On-Engine Dual Filter Option

48

QSL Fuel System Leakage Testing with On-Engine Filter Option


4918679 can be used to isolate the relief valve


3164618 can be used to isolate the injector return


3164618 can be used to isolate pump return from other returns

49